Step 4: Casing
Casing is the process of uniform-application of a top-dressing material on the spawn
run compost. Normally, materials having good water-holding capacity such as clay-loam field
soils or a mixture of peat moss and limestone or similar materials are used for casing. Rhizomorphs or mushroom bodies form on the surface of this casing and mushroom primordia,
or pins form on these rhizomorphs. Pasteurized materials should be used for casing to avoid
pest-disease infestations.
During spawning and casing, the compost temperature should be maintained in the
range of 75° to 80°F and thereafter, the compost temperature may be lowered about 2°F each
day until pinning or fruiting occurs. Water must be applied intermittently and a high relative
humidity must be maintained before the mushroom pins form.
To increase yield, urea or orchid fertilizer may be used after dissolving it in water @100
grams in 100 liters water. Using a plastic mist sprayer, the solution is sprayed on the surface immediately before fruiting or pinning.